The disclosure relates generally to automation and robotics, and more particularly, the disclosure relates to manipulator arms, end-effectors, and adapter mechanisms for manipulator arms and end-effectors. Still more particularly, the present disclosure relates to apparatus and methods for interchanging and operating manipulator arms and end-effectors.
The field of automation and robotics augments and extends human activities and exploration both on earth and in space. Stationary robots are common in industrial settings for repetitive tasks such as product assembly and packaging. Mobile robots work in a variety of indoor and outdoor settings, moving through varied terrain and in varied environmental conditions. Mobile robots travel on the ground, through the air, and through water to investigate difficult-to-reach locations, handle chemicals, collect environmental samples and data, patrol property, search for people trapped in rubble, and perform a variety of other tasks.
The physical work of a robot is performed by end-effectors mounted on manipulator arms. Mating adapters connect the end-effector to the manipulator arm and the manipulator arm to the body of the robot. The end-effector may be a hand tool, a power tool, a dexterous gripper, a scientific probe, a scoop, or any other attachable device that allows the robot to engage its surroundings. A manipulator arm connects an end-effector to the body of the robot and provides reach capability. A manipulator arm includes one or more segments or joints each with the ability to move in prescribed directions. Basic movements for joints include pitch, which is like the rotational motion of a human elbow, roll, which is like the motion of a human wrist when the hand is rotated about the forearm axis, and linear extension/retraction. Forming a manipulator arm from multiple joints gives the manipulator more flexibility, i.e., the ability to move in more directions. The objective is to move the end-effector toward a target and to engage the target. Basic movements for an end-effector include translation (up-down, forward-backward, and left-right) and rotation (clockwise and counterclockwise). Each of the three translational movements may be assigned to one axis of a coordinate system defined by three orthogonal, mutually perpendicular axes. The axes may be called x, y, and z. The orientation and starting point (origin) of the group of axes may be defined with reference to one of several places. For example, the orientation and origin may be established at a fixed spot within the region being explored (earth or moon), on the robot body, or at the connection point of the end-effector. The last two locations would define a moving and rotating coordinate system because the robot moves and turns.
The total number of independent, basic movements that a particular manipulator arm or an end-effector may make is known as its degrees-of-freedom (DOF). Three DOF are achieved by the translational movement along the three axes. Forward and reverse movement along any one axis is considered one DOF. When the end-effector is rotated clockwise or counter-clockwise around any of the three axes, this capability adds three more DOF, for a total of six DOF. Adding more joints to a manipulator arm adds more DOF.
When a manipulator arm is formed from joints with pitch and roll capabilities, performing a straight translational movement of the end-effector requires the simultaneous movement of multiple joints. Moving multiple joints simultaneously is governed by software algorithms stored in a computer or in another control system that may be on the main body of the robot or separate from the robot.
The work required of a particular robot may change, often requiring modifications to the robot. Common modifications or reconfigurations involve replacing the end-effector or the entire manipulator arm. If the new equipment has a different connecting adapter, the adapter on the robot must be either modified or replaced. If the new equipment has the same adapter as the previous manipulator or end-effector, then the exchange will be simpler but may still require significant effort. The end-effector and manipulator arm may be coupled by an adapter using threaded fasters such as bolts and nuts or machine screws, or coupled by clamps, or coupled by a pneumatically-actuated lock mechanism. These coupling methods require one or more tools or a source of compressed air. Furthermore, the exchange of an end-effector and manipulator arm typically requires adjustment to the controlling software to account for the reach, DOF, lift capability, and other parameters of the new equipment. Seemingly simple modifications to a robot can often be time-consuming and labor intensive.
Accordingly, there remains a need in the art for improved devices and methods for reconfiguring robotic manipulators arms and end-effectors.